The invention relates to processible compositions based on polar polymers and peroxide-vulcanizable compositions prepared therefrom.
Since the advent of highly polar polymers to commercial markets, they have been found extremely useful in preparing vulcanized products. Although laboratory peroxide-cured specimens of some of these polymers have been prepared, the properties of such vulcanizates have been considered inferior to the more conventionally vulcanized systems. A number of polar polymers such as chlorinated polyethylene and poly(vinyl chloride) have not effectively been vulcanized with peroxide type agents.
In their uncured state, polar polymers are tough materials which are difficult to handle at normal processing temperatures of about 100.degree. to 160.degree. C. To improve the processing characteristics of these polymers, physical plasticizers are used. These plasticizers are known to limit the crosslinking efficiency of peroxide vulcanizing agents, and in cases involving more conventional vulcanizing agents, plasticizers reduce some important vulcanizate properties.
It is known that peroxide crosslinking is a first order reaction whereby the rate of said reaction is independent of peroxide concentration or quantity of peroxide, but is primarily dependent on temperature. It has been found that the rate (half-life) of peroxide decomposition--which initiates polymer crosslinking--is strongly affected by the polymer, antioxidants, oils, plasticizers, and fillers comprising the vulcanizable compositions. These experimental facts, however, have not been unraveled to determine the reasons for this chemical behavior. Therefore, peroxide vulcanizates of polar polymers have not gained economic prominance and some of their unique properties remain unattainable.
My copending application, temporary Ser. No. 735,225 describes a novel process for the formation of crosslinkable compositions including these polar polymers.